Type of test Blood

Normal findings

Free testosterone, pg/mL

% Free testosterone

Adult male: 1.6%-2.9%

Adult female: 0.1%-0.3%

Total testosterone, ng/dL

Dihydrotestosterone

Adult male: 240-650 pg/mL

Adult female: ≤ 300 pg/mL

Test explanation and related physiology

 Testosterone levels are used to evaluate ambiguous sex characteristics, precocious puberty, virilizing syndromes in the female, and infertility in the male. This test can also be used as a tumor marker for rare tumors of the ovary and testicle.

Androgens include dehydroepiandrosterone (DHEA), androstenedione, and testosterone. DHEA is produced in the adrenal glands during cortisol and aldosterone formation, and it is also produced de novo by the testes or the ovaries. DHEA is the pre cursor of androstenedione, which is the precursor of testosterone (and estrogen).

Testosterone levels vary by sex and stage of maturity (indicated by Tanner stage). In men, most of the testosterone is made by the Leydig cells in the testicle; this accounts for 95% of the circulating testosterone in men. In women, about half of the testosterone is made by the conversion of DHEA to testosterone in the peripheral fat tissue. Another 30% is made by the same con version of DHEA in the adrenal gland, and 20% is made directly by the ovaries.

Physiologically, testosterone stimulates spermatogenesis and influences the development of male secondary sex characteristics. Overproduction of this hormone in a young male may cause precocious puberty. This can be caused by testicular, adrenal, or pituitary tumors. Overproduction of this hormone in females causes masculinization, which is manifested as amenorrhea and excessive growth of body hair (hirsutism). Ovarian and adrenal tumors/hyperplasia and medications (e.g., danazol) are all potential causes of masculinization in the female. Reduced levels of testosterone in the male suggest hypogonadism or Klinefelter syndrome.

Dihydrotestosterone (DHT) is the principal androgen made in body tissues, particularly the prostate. Levels of DHT remain normal with aging, despite a decrease in the plasma testosterone, and are not elevated in benign prostatic hyperplasia. Measurement of this hormone is useful in monitoring patients receiving 5 alpha-reductase inhibitor therapy, such as finasteride or chemotherapy, which may affect prostate function. It is also useful in evaluating patients with possible 5 alpha-reductase deficiency.

There are several testosterone stimulation tests that can be performed to more accurately evaluate hypogonadism. Human chorionic gonadotropin, clomiphene, and GnRH can be used to stimulate testosterone secretion.

17-Ketosteroids (17-KS) are metabolites of the testosterone and nontestosterone androgenic sex hormones that are excreted in the urine.

11-oxoandrogens (11-ketotestosterone, 11-hydroxytestosterone, and 11-hydroxyandrostenedione) are only made in the adrenal gland of men and women and are becoming increasingly used in the identification and surveillance of particular disease states. This panel of 11-oxoandrogens is analyzed using high- performance liquid chromatography-tandem mass spectrometry. They are elevated in patients with congenital adrenal hyperplasia and can be used to monitor therapy of this disease. Testicular adrenal rest tumors (TARTs) in men can be identified and treatment monitored with 11 oxo-androgen testing. 11-ketotestosterone has been shown to be in excess in polycystic ovary syndrome. Measuring 11-ketotestosterone as a marker of adrenal-specific androgens will provide additional information for monitoring GnRH agonist treatment prostate cancer.

Interfering factors

* Drugs that may cause increased testosterone levels include anticonvulsants, barbiturates, contraceptives. estrogens, and oral

* Drugs that may cause decreased testosterone levels include alcohol, androgens, dexamethasone, diethylstilbestrol, digoxin, ketoconazole, phenothiazine, spironolactone, and steroids.

 Procedure and patient care

 • See inside front cover for Routine Blood Testing.

• Fasting: no

• Blood tube commonly used: red

• Because testosterone levels are the highest in the early morning hours, blood should be drawn in the morning.

Abnormal findings

 Increased levels (male)

- Idiopathic sexual precocity

- Pinealoma

- Encephalitis

- Congenital adrenal hyperplasia

- Adrenocortical tumor

- Testicular or extragonadal tumor

- Hyperthyroidism

- Testosterone resistance syndromes

Increased levels (female)

- Ovarian tumor

- Adrenal tumor

- Congenital adrenocortical hyperplasia

- Trophoblastic tumor

- Polycystic ovaries

- Idiopathic hirsutism

Decreased levels (male)

- Klinefelter syndrome

- Cryptorchidism

- Primary and secondary hypogonadism

- Trisomy 21 (Down syndrome)

- Orchidectomy

- Hepatic cirrhosis

اخر الاخبار

اخبار العتبة العباسية المقدسة

اللجنة المنظّمة: مهرجان رحمةً للعالمين يسعى لإحياء مبدأ التعايش السلمي والحوار الحضاري

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المزيد

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المزيد

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المزيد

مواضيع ذات صلة

thromboelastography (Thromboelastometry)

throat and nose cultures

Biomarkers of Stroke

Soluble IL-33 Receptor (sST2)

syphilis detection test (Serologic test for syphilis [STS], Venereal Disease Research Laboratory [VDRL], Rapid plasma reagin [RPR], Fluorescent treponemal antibody test [FTA])

sweat test (Sweat electrolyte test, Sweat chloride test, Sweat conductivity test, Iontophoretic sweat test)

substance abuse testing (Urine drug testing, Drug testing, Drug screening, Toxicology screening)

Streptococcus serologic testing (Antistreptolysin O titer [ASO], Antideoxyribonuclease-B titer, [Anti-DNase-B, ADNase-B, ADB], Streptococcus group B antigen detection, Streptozyme)

Galectin-3

Biomarkers of Collagen Synthesis and Degradation

Cardiac Fibrosis

stool for leukocytes (White blood cell stool test, Fecal leukocyte stain, Stool for white cells)